title: Profound hyperventilation and development of periodic breathing during exceptional orthostatic stress in a 21-year-old man.
abstract: In this case report we describe a trial of experimentally induced syncope in a healthy young volunteer that produced abnormal periods of hyperventilation (V(A)=57 L/min) and periodic breathing; the latter persisting for approximately 60 min following termination of the trial. In this example, independent of systemic hypotension, the severe hyperventilation and related hypocapnia (end-tidal PET(CO2)) induced by orthostatic stress (lower body negative pressure) resulted in a ∼65% reduction in cerebral blood flow velocity. Potential mechanisms underlying these striking cardiorespiratory patterns are discussed.
authors.affiliation: Department of Physiology, University of Otago, Dunedin, New Zealand. donjo492@student.otago.ac.nz
authors.forename: Joseph
authors.initials: J
authors.lastname: Donnelly
authors.forename: Samuel J E
authors.initials: SJ
authors.lastname: Lucas
authors.forename: Kate N
authors.initials: KN
authors.lastname: Thomas
authors.forename: Sean D
authors.initials: SD
authors.lastname: Galvin
authors.forename: Philip N
authors.initials: PN
authors.lastname: Ainslie
mesh_terms: D006801:Humans; D006985:Hyperventilation / Q000209:etiology / Q000503:physiopathology*; D016857:Hypocapnia / Q000209:etiology / Q000503:physiopathology*; D008150:Lower Body Negative Pressure / Q000009:adverse effects; D008297:Male; D012119:Respiration; D013575:Syncope / Q000209:etiology / Q000503:physiopathology*; D055815:Young Adult